A biscuit eater is a derogatory term for a dog too sorry to hunt anything but his own food. Can also be used for a person who is slow, lazy, or selfish.
Biscuit eater can be used in place of bitch in the phrase “son of a bitch” since both are terms for a dog.
Southerners use it as a way to cuss without using a curse word.
That “son of a biscuit eater” has run off with his tramp again.